The nail has stained the surrounding wood black, so you have a bigger problem than just filling the hole. I am with Jim that the best solution is a patch, larger than the hole itself, made with solid wood selected to match grain and color as well as you can.
I have used all sorts of tricks with sawdust, etc. to hide something, but the general problem is that it is not wood (even if it is sawdust of the same wood, mixed with glue, epoxy, or shellac). Therefore, even if you get a perfect match today, it will age differently than the surrounding material, so will become obvious later. Wood filler sticks have the same problem - they aren't the same material, so they age differently.